(a) Field of the Invention
This disclosure relates to a method of preparing a porous polybenzimidazole.
(b) Description of the Related Art
A highly permeable polymer membrane has drawn attention as a gas separation membrane (Park, H. B. et al., Science, 2007. 318 5848 p. 254-258; Koros, W. Jet al., Journal of Membrane Science, 1993. 83 1 p. 1-80; Robeson, L. M. et al., Polymer, 1994. 35 23 p. 4970-4978).
Glassy polymers such as poly(1-trimethylsilyl-1-propyne) (PTMSP) and a polymer with intrinsic microporosity (PIM) have been reported to have high gas permeability due to cavities present in the glassy polymer matrix (Langsam, M. et al., Gas Separation and Purification, 1988. 2 4 p. 162-170; Langsam, M et al., Polymer Engineering and Science, 1989. 29 1 p. 44-54; Srinivasan, R. et al., Journal of Membrane Science, 1994. 86 1-2 p. 67-86). Such glassy polymers have extensive applicability at a high temperature and high gas permeability, and therefore are applicable as a separation membrane. However these types of glassy polymers show a limited and low gas selectivity.
Polybenzimidazole has excellent high temperature characteristics (Q. Z. Liu et al., Polymeric Materials Science and Engineering, 2005. 21 p. 29; Herward Vogel et al., Journal of Polymer Science, 1961. 50 154 p. 511-539), high glass transition temperature (Tg=425-435° C., He, R. et al., Journal of Membrane Science, 2006. 277 1-2 p. 38-45), excellent mechanical stability (Tsur, Y. et al., Journal of Polymer Science Part A-1 Polymer Chemistry, 1974. 12 7 p. 1515-1529), and chemical stability against hydrolysis reactions of acids or bases (Q. Z. Liu et al., Polymeric Materials Science and Engineering, 2005. 21 p. 29;). Therefore, it may be appropriately applicable as a high temperature fiber, a cationic conductive polymer, etc. (Li, Z. X. et al., Journal of Polymer Science, Part A: Polymer Chemistry, 2006. 44 19 p. 5729-5739).